I was under the impression that Quench is the distance of the closest part of the piston in relationship to the chamber in the head, whether it is Flat, Dish or Dome.
What we refer to as "quench" is the distance between the top surface of any piston, and the portion of the chamber roof, furthest from the spark plug and is kind of a slang term now. It's not the same as piston to head clearance although on a quench-built engine it is usually the closest those two parts get. Quench is really the effect as the KB site says and the quench distance is what you are refering to. Dishes, domes, and flat tops, and open or closed chambers all bring thier own variables to the build if you want to build to maximize the quench effect.
